Sorry, not good enough. If that were true, why are babies (who are as close to being blank slates as possible) not different from one another? Why aren't these differences "revealed" until the children have had enough human interaction to influence their behavior?
Yes yes. I knew I would not be able to get away with anecdotal evidence on any thread here.
So I came home from the Dr. (she has strep, and apparently so do I) and did some googling on fine motor skill development in girls vs boys. Apparently the parents at my daughter's preschool were not the first human beings on earth to notice the difference.
So here are some popular (as opposed to scholarly) sources that state the girls develop fine motor skills earlier than boys, and that boys develop gross motor skills earlier than girls. http://www.ehow.com/list_7348853_differences-skills-between-boys-girls.html
Here is another article that discusses brain functions in girls and boys. This is talking more about teenagers than little kids.
The Minds of Girls
• By adolescence, a girl’s corpus callosum is 25 percent larger than a boy’s. The corpus callosum is the bundle of nerves that sends signals across the two parts of the brain. This enables more “cross talk” between hemispheres. Because of the greater cross talk, girls are able to multitask better than boys.
• Girls have fewer attention span problems and can make faster transitions between lessons.
• Stronger neural connectors create better listening skills, more detailed memory storage, and better discrimination among the tones of voice.
• A girl’s stronger neural connectors and a larger hippocampus provide greater use of sensory memory details in speaking and writing.
• Girls’ prefrontal cortex develops earlier and is larger than boys’.
• Girls have more serotonin and make fewer impulsive decisions than boys. Teenagers don’t think of the consequences of their actions. They act on impulse. It is the serotonin and oxytocin that tell a teenager to slow down and think about what could happen if they did something. “Our jobs as adults is to serve as external frontal lobes.”
• A girl’s brain also experiences approximately 15% more blood flow, which is located in more centers of the brain than a boy’s.
• With more cortical areas devoted to verbal functioning, girls are better at: sensory memory, sitting still, listening, tonality, mental cross talk, and the complexities of reading and writing, i.e. the very skills and behaviors often rewarded in schools.
The Minds of Boys
• Boys have more cortical area devoted to spatial-mechanical functioning and half as much to verbal-emotive functioning.
• “For many tasks, brain imaging studies show that women use the most advanced areas of the brain, the cerebral cortex, whereas men doing the same task use the more primitive areas …In adolescence, a larger fraction of the brain activity [in girls] associated with negative emotion moves up to the cerebral cortex. So, the 17 year old girl is able to explain why she is feeling sad in great detail...In boys the locus of brain activity associated with negative emotion remains stuck in the amygdala. Asking a 17 year old boy to explain why he’s feeling glum may be as productive as asking a 6 year old boy the same question.” Source: Sax, Leonard (2005) Why Gender Matters. New York: Broadway Books.
• Spatial-mechanical functioning makes boys want to move objects through the air, such as balls, airplanes, their little sisters, or just their arms and legs.
• “Boys are significantly more likely [than girls] to do something dangerous. Risky and dangerous activities trigger a ‘fight or flight’ response that gives a tingle, a charge, an excitement that many boys find irresistible. Boys systematically overestimate their own ability, while girls are more likely to underestimate their abilities.” Source: Sax, Leonard (2005) Why Gender Matters. New York: Broadway Books.
• Boys have less serotonin and less oxytocin, which makes them more impulsive and less likely to sit still to talk to someone.
• Boys have less blood flow to the brain and tend to structure or compartmentalize learning.
• The male brain is designed to go into rest states in which it renews, recharges, and reorients itself. Girls do this without going to sleep.
• The more words a teacher uses, the greater chance a boy will quit listening.
• Boys’ brains are better suited to symbols, abstractions, and pictures. Consequently, boys generally learn higher math and physics better than girls. Boys prefer video games for the physical movement and destruction. And boys get into more trouble for not listening, moving around, sleeping in class, and incomplete assignments. http://crr.math.arizona.edu/GenderKeynote.pdf
I can't help but think that this is more than social conditioning.